The present invention relates to a recording disk apparatus in which signals are recorded onto and/or read out from a recording disk through a magnetic or optical (electro-optical, magneto-optical or the like) head while the recording disk is rotated by a motor and the head is moved by a servomotor, and to a recording disk rotating apparatus for supporting and driving the recording disk to be rotated in the recording disk apparatus.
In the prior-art rotational supporting structures for recording devices and the prior-art magnetic fluid seals therefor, a magnet for providing a magnetic fluid seal is arranged at a rotary side and a thrust bearing portion has spiral or herring-bone lubricant grooves as disclosed in JPA Hei 3-272318, a magnet for magnetic fluid bearing lubricant is arranged at a stationary side and the thrust bearing portion has a magnet bearing as disclosed in JPA Hei 4-6667, the magnetic fluid seal is used for a ball-bearing spindle as disclosed in JPA Hei 3-89079, and the magnetic fluid seal has projections extending from the magnet toward a shaft as disclosed in JPA Sho 59-110961 and JPA Hei 1-234662.